Mechanical Technology October 2015

⎪ Structural engineering materials, metals and non-metals ⎪

no longer required when a protective lining is being applied on top with a 24-hour overcoat window, thus reduc- ing application costs. • Application is also simplified with mixing and application possible at temperatures as low as 10 °C (50 °F). • The rubbery domains used in Belzona 1523 and Belzona 1593, which were also incorporated in the polymer ma- trix of Belzona 1511, have improved the adhesion, flexibility and toughness of Belzona 1511. Tensile shear adhe- sion (ASTM D1002) has increased by 46% regardless of the cure tempera-

should be ground down to a smooth contour with a radius of not less than 3.0 mm. All surfaces must then be grit blasted using an angular abrasive to Swedish Standard SA 2½ (near white metal finish) with a minimum profile of 75 microns. 4. Paste grade epoxy material must be mixed in the correct ratio. 5. The material needs to be applied onto the substrate until the original wall thickness is restored. 6. The material must be allowed to so- lidify at ambient temperatures before achieving full cure in service. One drawback traditionally associated with the use of epoxy materials for pit- ting repairs has recently been overcome, namely the amine bloom film that would appear on the surface during curing. The bloom would manifest in the form of sticky deposits that affected overcoat- ability and intercoat adhesion. It had to be removed by first washing with a hot detergent solution followed by a fresh water wash, and then frost blasting prior to the application of a protective coating on top of the pitting repair, leading to ex- tended application time and labour costs. The latest innovation in raw materials has brought on non-bloom technology, where frost blasting of the applied mate- rial prior to the application of protective lining is not required. This feature was incorporated into the reformulated ver- sion of the Belzona 1511 (Super HT- Metal), which has been on the market since 2001. In addition to incorporating non-bloom technology, further evaluation revealed the following enhanced features: • Frost blasting of the Belzona 1511 is

ture. Pull off adhesion has increased by 34% (ASTM D4541/ ISO 4624). Continuous advancements in raw ma- terials make it possible for coating and composite manufacturers to produce systems that are better value and easier to apply, at the same time minimising the risks typically associated with hot work. In this way, the indirect costs of corrosion, including downtime, delays, litigation and other unplanned overheads, can be significantly reduced. Belzona compounds are distrib- uted and supported in South Africa by AESSEAL. q

About Belzona Established in 1952, Belzona has pioneered innovative polymer technology that has revo- lutionised industrial repair and maintenance procedures. The company is a leader in the design and manufacture of polymer repair com- posites and industrial protective coatings for the repair, protection and improvement of machinery, equipment, buildings and structures. The full Belzona product range is manu- factured in Harrogate, England, to stringent quality and environmental control guidelines to comply with the requirements of ISO 9001:2008 and ISO 14001:2004. As well as AESSEAL in South Africa, Belzona has over 140 distributors in more than 120 countries ensuring not only the availability of Belzona materials, but also specification support, project manage- ment, application and supervision services. Distributorships and their teams are sup- ported by Belzona Corporate offices in Europe, North America and Asia.

About AESSEAL AESSEAL is a specialist in the design and manufacture of mechanical seals and sup- port systems. The company’s mechanical seals are used in a wide range of pumps and rotat- ing equipment worldwide to prevent liquids and gases escaping into the environment. AESSEAL manufactures mechanical seal types to suit all industries and its investment in modular designs means that it can provide the best on-time delivery performance in the industry. The AESSEAL range of seals, seal sup- port systems and bearing protectors are all designed to improve pump reliability and reduce maintenance costs. The business is built around giving customers such excep- tional service that they need never consider alternative sources of supply. AESSEAL operates from 230 locations in 104 countries, including nine manufacturing and 58 repair locations, and has more than 300 customer service representatives who visit industrial plants every day. q

Figure 3: A paste grade epoxy material was chosen to fill the pits and afterwards, the wall was protected with a modified epoxy novolac coating.

Figure 4: In July 2015, after four years in service, the reboiler was again opened up for inspection. No further pitting damage or corrosion was identified.

Mechanical Technology — October 2015

33